Many types of devices are used in wireless applications. For example, cell phones, laptops, mobile devices, smart phones and the like are devices that communicate wirelessly and utilize wireless application for different types of communications. Oftentimes these devices include multiple receivers for different communication functions. In a wireless device in which multiple receivers share the same radio frequency input, such as the case where an antenna and its associated filters and/or switches are shared by a plurality of receivers, oftentimes the different receivers are for different types of communication systems such as Wi-Fi, Bluetooth, GPS and the like.
FIG. 1 illustrates a block diagram of a conventional dual receiver 10. The dual receiver 10 includes a receiver front end 18 coupled to a plurality (in this case two) of receiver subsystems 20. The receiver front end 18 comprises an antenna 12 and programmable amplifier 14. The programmable amplifier 14 can be adjusted to provide variable gain amplification to the signal received by the antenna. Each of the receiver subsystems 20 include a mixer 22a, 22b coupled to an amplifier 24a, 24b which in turn provides an output signal 26a, 26b. 
In order to achieve an optimal receiving performance, such as sensitivity, the plurality of receiver subsystems 20 are usually connected together after a pre-amplifier 14 to minimize the degradation to the overall system sensitivity due to the signal splitting power loss. Each of the receiver subsystems 20 usually needs a different amount of pre-amplifier 14 gains because the strengths of the signals each receiver subsystem 20 intends to receive (usually at different frequencies) can be different. Therefore, it is desirable for the common front-end circuit 18 to be able to provide different amounts of amplifications for each of the receivers simultaneously which the conventional dual receiver 10 can not achieve.
A conventional method to optimize the dual receiving performance is by over-designing each of the plurality of receivers such that each of the plurality of receiver subsystems 20 can tolerate the maximum possible incoming signal power with a fixed pre-amplifier gain that is common to both receivers.
Another conventional method is to adjust the front-end gain for optimal reception of the large input signal of one selected receiver. The performance of the other one of the two receivers is usually degraded when the selected pre-amplifier is too high or two low for the non-preferred receiver.
A third conventional method is by timesharing the operation of the two receivers so that each of the two receivers can set an optimal front-end gain when it is active. The problem with this method is that it does not allow for use of the plurality of receiver subsystems at the same time.
Accordingly, there is a need for an efficient and cost effective way for the plurality of receiver subsystems in a wireless device to operate at their respective optimal settings to achieve maximum dynamic range. The present invention addresses such a need.